Method of and apparatus for dispensing magnetic powder



March 20, 1962 w P. VAN DEN BLINK 3,026,406

METHOD OF AND APPARATUS FOR DsPENsING MAGNETIC POWDER March 20, 1962 w, P. VAN DEN BLINK 3,026,406

METHOD 0E AND APPARATUS FOR DTsPENsING MAGNETIC POWDER Filed April 8. 1960 2 sheets-sheet 2 fm E-R W16 FIG.3

INVENTOR WILLEM P. VAN DEN BLINK.

By s

j A R. W AGEN United States at@ 3,026,406 METHOD F AND APPARATUS FORV DISPENSING MAGNETIC POWDER Willem Pieter van den Blink, Utrecht, Netherlands, as-

signor to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed Apr. 8, 196,0, Ser. No. 20,863 Claims priority, application Netherlands May 1, 1959 4 Claims. (Cl. Z19-130) In certain types of automatic arc welding, for instancel the type described in U.S. Patents 2,803,740V and 2,820,137, magnetic powder is used in place of, or in addition to, a protective gas and is magnetically held against the electrode wire by means of the magnetic field produced by the welding cur-rent passing therethrough. In such welding it is necessary to control .accurately the quantity of magnetic powder supplied per unit time, and it Ihas been proposed to accomplish this yby means of various mechanical devices which act directly upon the powder.

I have found that such mechanical devices have certain disadvantages. More particularly, there is considerable friction between the magnetic powder and the parts which move in contact therewith, and this not only causes undue wearing of such parts but also causes difticulties in any gears, bearings, etc. which are employed in connection with such parts. In Iaddition it frequently happens that there is irregular packing of the material which causes non-uniformity in the amounts of powder dispensed.

In accordance with my invention l have found that the above diiculties are overcome and accurate and uniform dispensing of magnetic powder is obtained by feeding the powder through la passageway formed by a member of non-magnetic material and periodically applying to -axially displaced points within the passageway, magnetic fields which temporarily hold portions of the powder.

In accordance with a specic embodiment of the invention, the dispensing device includes an assembly of a plurality of segment-shaped permanent magnets spaced from each other axially on a shaft and also displaced relatively to each other in a plane perpendicular to the shaft. This assembly is mounted within a :tubular member of non-magnetic material surrounded by a second tubular member to form an annular passageway through which the magnetic powder passes and in which the magnetic lields are effective.

I provide means 4to control the rate at which the magnetic powder is dispensed, and when used in automatic `arc welding of the above type this rate is controlled by the speed at which the electrode wire is supplied. In cases where it is desired to dispense certa-in portions of the powder at spaced time intervals, I may control the amounts of the portions by changing the distance between the points at which the magnetic fields are applied.

In order that my invention may be clearly understood and readily carried into etlect, I shall describe the same in more 4detail in connection with specific apparatus and with reference to the accompanying drawing in which "are FIGURE l is a sectional side View of a portion of an arc-welding apparatus embodying a dispensing device according to the invention,

FIG. 2 is a perspective view of a portion of FIGURE 1, and

FIG. 3 is a section side view o-f a dispensing device according to another embodiment of the invention.

The welding apparatus shown in FIGURE l comprises a hopper 2 of a non-magnetic material, such as copper, having a `conical-shaped upper portion containing -a supply of .a magnetic powder 1, such as described in the abovementioned Patent 2,803,740. Hopper 2 has -a lower tubular portion with a conical-shaped end forming a narrow annular passageway -4 with Ia tubular member 3 of non-magnetic material supported near its top by a flange portion of hopper 2. Fixedly supported by a projection 15 of tubular member 3 is a bent tube l1 extending through member 3 and hopper 2. An electrode wire 9, which may be of any of the well-known compositions, is moved through tube 9 in the direction of Kthe arrow by two rollers 10 driven by suitable driving means (not shown).

Magnetic powder `1 flows by gravity into the annular passageway 4 and, in accordancewith the invention, is dispensed at the desired rate -by means of a dispensing mechanism comprising a shaft 7 rotatably mounted on two bearings 13 and 14 forming part of tubular member 3. Fixedly mounted on the lower end of shaft 7 are two similar-shaped permanent magnets 5 and 6 (see FIG. 2) having magnetic poles at the positions indicated and relatively displaced at an angle, as shown 180, in a plane perpendicular to the axis of shaft 7. Magnets 5 and 6 are so di-mensioned that their peripheral surfaces form only a small clearance with the inner surface of member 3 and produce magnetic lields which extend into annular space 4 as indicated. When shaft 7 is rotated about 180 from the position shown a portion of powder 1, which is being held by the iield of magnet 5 will be released by this field, but will :be temporarily held by the ield of magnet 6. When the shaft is then rot-ated into the position shown the portion temporarily held by lthe field of magnet 6 will be released. Thus, the magnetic powder will be continuously dispensed downwardly through annular space 4, and the quantity dispensed within a unit time will depend upon the speed of Irotation of shaft 7. v

Upon leaving the lower end of annular space l powder 1 is attracted to the surface 'of electrode wire 9 by the magnetic field produced by the flow of welding current therethrough.

In order that the proper amount of magnetic powder will be dispensed, the speed of rotation of the magnets is made dependent upon the speed at which the electrode wire 9 is supplied. For this purpose shaft 7 is` provided on its upper end with pulley 8 driven by a `belt 12 passing over two idling pulleys 36 and a driving pulley fixedly mounted on the shaft of the upper roller 10. Instead of bringing the electrode wire 9 in at an angle, the construction of the device could, of course, be such 'that the wire is moved vertically downward and the powder is fed from the side.

The dispensing device illustrated in FIGURE 3 is used to dispense measured quantities of powdered magnetic material in a series of molds 16 carried by a belt in the direction indicated by the arrow. The device comprises a hopper 17 of non-magnetic material containing a supply of magnetic powder 18, Supported yfrom hopper 17 by means of a bracket 19 are two electricallyactuated devices 20 and 21 of similar construction each comprising a permanent magnet 22 `supported on the end of a core 23` of a solenoid 24 and spring biased tow-ard hopper 17. Devices 20 and 21 are so supported on bracket 19 as to be movable with respect to each Vother and thereby vary the distance between magnets 22 and thus the `amount ofthe powder 18 which is dispensed Ito each of the molds 16.

The solenoids of devices'20 and 21 yare selectively energized from a `suit-able voltage supply 25 by means of a single-pole double-throw relay 26.v I2F01' this purpose one terminal of supply 25 is connected to the -heel of armature Z6 Iwhich in the de-energized position shown engages a lower contact 27 connected to one terminal of the solenoid of device 21, and in its energized position engages an upper contact 2S connected to one terminal of the solenoid of device 2t). The other terminals or" the Y .solenoids of devices 20 and 21 are connected to the other terminal of supply 25. The coil of `relay 26 has one terminal connected to-fone terminal of sup-ply 25,

. and its other terminal connected through a switch 29 to the other terminal of `supply 2,5.

With the apparatus in the position shown, the powder 18 is held in position by means of'magnet 22 of device 20. When switch 29 is closed magnet 22 of the device v20 is moved away fromv hopper 17, whereas the magnet,

Z2 of device 21 is moved in close proximity to the hopper whereby the powder 1S falls down through the passageway and is held in its Ilower position. When contact 29 is open the magnets 22 -are returned to the position shown whereby the portion of the material i8 inthe passageway between the two magnets 22 is deposited in j i passageway, producing -a second magnetic field displaced f at an :angle lfrom said first eld and extending through ,only a portion of the passageway, `and rotating-said second Atiield in a planespaced from the V plane of rotation of said first field.

2. A device for dispensing magnetic powder comprising two tubular members forming an annular passageway for said powdery-a magnet rotatably mounted within the inner member with its magnetic field extending within the passageway, a second magnet secured to :said rst magnet with its magnetic eld extending into the passageway and displaced angularly and axially with Vrespect to the iield of the first magnet, and means to rotate said magnets to thereby dispense the powder.

3. An arc-welding apparatus comprising means -to supply an electrode wire t0 ian operating point, 'an inner tubular member and an outer tubular member forming an annular passageway adapted to transport magnetic powder and having an outlet adjacent the electrode wire,` a segment-shaped magnet rotatably arranged within said inner member with its magnetic eld. passingthrough a portion of the passageway, a second magnet secured to said first magnet with its magnetic field angularly displaced with respect to the field of the first magnet and passing through afportion of the passageway axially displaced from said first port-ion, and means to rotate said magnets.

4. A device for dispensing magnetic powder compris-v der, 'first magnetic means rotatably-mounted within said rst means to produce amagnretic'iield extending over only a segment of the passageway, second magnetic means rotatably-mounted within said irst means to produce a second iield extending over only a segment of said `passageway and displaced axially andangularly from the first magnetic field, Vand means to rotate said` two magnetic means andy iields.

References Cited in thefile of this patent UNITED STATES PATENTS 2,415,376 Strickland n Feb. 4, 1947 2,718,856 Gathercoal Sept.'27, 1955 2,805,323 `Cushman ctl. Sept. 3, 1957 2,820,137 Ghemar et al.v Jan. 14,1958 2,929,910 Kennedy 22, 1960 

1. A METHOD OF DISPENSING MAGNETIC POWDER COMPRISING THE STEPS OF INTRODUCING THE POWDER INTO A PASSAGEWAY, PRODUCING A MAGNETIC FIELD EXTENDING INTO ONLY A PORTION OF THE PASSAGEWAY, ROTATING SAID FIELD AROUND THE PASSAGEWAY, PRODUCING A SECOND MAGNETIC FIELD DISPLACED AT AN ANGLE FROM SAID FIRST FIELD AND EXTENDING THROUGH 